Before segmental construction entered everyday vocabulary, one project quietly transformed bridge erection. Across the tidal flats of western France, Jean Müller and Campenon-Bernard built the Oléron Viaduct (Pont de l'île d'Oléron) — a 2.86 km prestressed-concrete structure that became the first viaduct in the world erected with a launching gantry (poutre de lancement).

2.86 km
Structure length
46
Spans
79 m
Typical main span
1964
Construction start
Constraint 1
Traditional barge or crane lifting was impractical given the shifting tidal conditions of the Coureau d'Oléron. The site dictated the method.
Müller's solution
A self-advancing overhead steel gantry, resting on the piers and placing precast segments symmetrically to build 79 m spans, span by span — avoiding all contact with the water below.
Precision erection
Each segment was lifted, aligned, and post-tensioned with high geometric precision — entirely from above, without touching the water below.

The concept proved that large viaducts could be erected entirely from above, safely and efficiently — setting the template for modern launching gantries used worldwide today.

The principle Müller demonstrated at Oléron — that precast segments could be assembled span-by-span from an overhead system resting on the permanent piers — became the foundation for subsequent launching gantry development worldwide. The site constraints that appeared to make the project impractical were what forced the invention.

The erection principle proven at the Coureau d'Oléron set the template for how major viaducts are built from above. The method was not adopted because it was obvious. It was adopted because it was demonstrated — here, with precision, under tidal constraint, for the first time.